In crushing of hard materials, for example blocks of stone or ore, use is often made of a crusher of the gyratory crusher type. One example of a gyratory crusher is disclosed in U.S. Pat. No. 4,192,472. The gyratory crusher disclosed therein has an oil sump, which collects lubricating oil that has been pumped to the crusher's bearings for lubrication thereof. The lubricating oil is then pumped from the oil sump back to the bearings.
A problem associated with the crusher disclosed in U.S. Pat. No. 4,192,472 is that it is often difficult to start the crusher at low ambient temperatures, because under such conditions the lubricating oil is viscous and difficult to circulate in the crusher.